The present invention relates to the connection of tee or branch assemblies to pipelines such as gas or water mains and the repair of damaged such pipelines or water mains basically using two half-shells which are secured together to form a shell assembly which encircles the pipelines leaving an annulus between the pipeline and the shell assembly.
According to the invention, a method is provided for securing a shell assembly to a pipeline, wherein the shell assembly comprises a first part for locating on the side of the pipeline remote from a side which is damaged or from which a branch is to extend, and a second part, optionally incorporating a branch, for locating on the side that is damaged or from which the branch is to extend, the method comprising positioning a containment ring on the pipeline at the required position on the pipeline and surrounding the damaged area or the area from which the branch is to extend, positioning an annular seal on the pipeline so that the seal is wholly radially within the containment ring, positioning the second part of the shell assembly onto the seal, positioning the first part of the assembly on the pipeline and securing the first and second parts together so as to compress the seal and leave an annular space between the first and second parts and the external surface of the pipeline, providing sealing means for substantially preventing fluid from escaping from the annular space, wherein the upper and lower sides of the containment ring are each provided with an annular groove, with the annular grooves being connected to each other by a plurality of passages extending through the ring from one groove to the other, and introducing sealant via a hole provided or made in the wall of the assembly, into the upper groove to fill the lower groove, the passages and the upper groove to provide sealing between the containment ring and the pipeline, and between the containment ring and the assembly.
Grout may be introduced into the annular space that bonds the branch assembly in position on the pipeline on curing.
In the case where the second part incorporates a branch, it will be appreciated that subsequent to the shell assembly becoming secured in position on the pipeline, a known procedure can be executed for cutting a coupon out of the pipeline via access through the branch under xe2x80x9clivexe2x80x9d conditions of the pipeline.
It will also be appreciated that the annular seal must be sufficiently compressible, and ideally also sufficiently robust to withstand and contain with the containment ring line pressure during operation of the pipeline over the working pressures.
If grout is used it may, for example, be selected from the following range: urethanes, polyesters, acrylics, epoxies and cemtatious compounds. It will be appreciated that each should be selected to satisfy the operating temperature, humidity and curing rate which then leads to the different adhesion strengths for different applications. Different grout material provides a different exothermic reaction which will determine the volume change after installation. It will also be understood that the volume change of epoxy grout should be optimized to minimize the internal stress system within the grout.
In order to ensure there is a good key for the grout, the external surface of pipeline and the inner surface of the first and second parts of the branch assembly may be dressed up or grit blasted prior to the assembly being mounted on the pipeline.